public async Task Save(IEnumerable <Uri> uris)
{
if (uris == null)
{
throw new ArgumentNullException(nameof(uris));
}
var websites = uris.Select(u => new Website
{
Id = Guid.NewGuid(),
Uri = u
});
await _websiteRepository.Clear().ContinueWith(t => _websiteRepository.Save(websites));
}